[clang/clang-tools-extra] Fix BZ44437 - add_new_check.py does not work with Python 3

[kwk]

Summary

This fixes https://bugs.llvm.org/show_bug.cgi?id=44437.

Thanks to Arnaud Desitter for providing the patch in the bug report!

A simple example program to reproduce this error is this:

#!/usr/bin/env python

import sys

with open(sys.argv[0], 'r') as f:
  lines = f.readlines()
lines = iter(lines)
line = lines.next()
print(line)

which will error with this in python python 3:

Traceback (most recent call last):
  File "./mytest.py", line 8, in <module>
    line = lines.next()
AttributeError: 'list_iterator' object has no attribute 'next'

Here's the same strategy applied to my test program as applied to the add_new_check.py file:

#!/usr/bin/env python

import sys

with open(sys.argv[0], 'r') as f:
  lines = f.readlines()
lines = iter(lines)
line = next(lines)
print(line)

The built-in function next() is new since Python 2.6: https://docs.python.org/2/library/functions.html#next

[dsanders]

LGTM

[kwk]

This comment was removed by kwk.

clang-tools-extra/clang-tidy/add_new_check.py

with open(filename, 'w') as f:
     check_added = False
     check_fq_name = module + '-' + check_name
     check_decl = ('    CheckFactories.registerCheck<' + check_name_camel +
                   '>(\n        "' + check_fq_name + '");\n')
 
     lines = iter(lines)
     try:
       while True:
-        line = lines.next()
+        line = next(lines)
         if not header_added:
           match = re.search('#include "(.*)"', line)
           if match:
             header_found = True
             if match.group(1) > check_name_camel:
               header_added = True
               f.write('#include "' + check_name_camel + '.h"\n')
           elif header_found:
             header_added = True
             f.write('#include "' + check_name_camel + '.h"\n')
 
         if not check_added:
           if line.strip() == '}':
             check_added = True
             f.write(check_decl)
           else:
             match = re.search('registerCheck<(.*)> *\( *(?:"([^"]*)")?', line)
             prev_line = None
             if match:
               current_check_name = match.group(2)
               if current_check_name is None:
                 # If we didn't find the check name on this line, look on the
                 # next one.
                 prev_line = line
-                line = lines.next()
+                line = next(lines)
                 match = re.search(' *"([^"]*)"', line)
                 if match:
                   current_check_name = match.group(1)
               if current_check_name > check_fq_name:
                 check_added = True
                 f.write(check_decl)
               if prev_line:
                 f.write(prev_line)